mm/swap: make page_swapcount and __lru_add_drain_all static

Make page_swapcount and __lru_add_drain_all static.  They are only used
within the file now.

Link: https://lkml.kernel.org/r/20220509131416.17553-9-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/swap.h

@@ -485,7 +485,6 @@ int swap_type_of(dev_t device, sector_t offset);
 int find_first_swap(dev_t *device);
 extern unsigned int count_swap_pages(int, int);
 extern sector_t swapdev_block(int, pgoff_t);
-extern int page_swapcount(struct page *);
 extern int __swap_count(swp_entry_t entry);
 extern int __swp_swapcount(swp_entry_t entry);
 extern int swp_swapcount(swp_entry_t entry);
@@ -557,12 +556,6 @@ static inline void put_swap_page(struct page *page, swp_entry_t swp)
 {
 }
 
-
-static inline int page_swapcount(struct page *page)
-{
-	return 0;
-}
-
 static inline int __swap_count(swp_entry_t entry)
 {
 	return 0;

mm/swap.c

@@ -748,7 +748,7 @@ static void lru_add_drain_per_cpu(struct work_struct *dummy)
  * Calling this function with cpu hotplug locks held can actually lead
  * to obscure indirect dependencies via WQ context.
  */
-inline void __lru_add_drain_all(bool force_all_cpus)
+static inline void __lru_add_drain_all(bool force_all_cpus)
 {
 	/*
 	 * lru_drain_gen - Global pages generation number

mm/swapfile.c

@@ -1429,7 +1429,7 @@ void swapcache_free_entries(swp_entry_t *entries, int n)
  * This does not give an exact answer when swap count is continued,
  * but does include the high COUNT_CONTINUED flag to allow for that.
  */
-int page_swapcount(struct page *page)
+static int page_swapcount(struct page *page)
 {
 	int count = 0;
 	struct swap_info_struct *p;